DE102009058273A1 - Method and device for fixing textiles and textile product produced thereby - Google Patents

Abstract

The invention relates to a method for fixing at least two textiles to each other, which overcomes the problems normally encountered during sewing. The invention also relates to a device for carrying out such a method and to a textile product produced or producible by the method.

Description

The invention relates to a method for fixing at least two textiles to each other, which overcomes the problems normally encountered during sewing. The invention also relates to a device for carrying out such a method and to a textile product produced or producible by the method.

The preforming and handling of dimensionally unstable textile fabrics presents a major challenge in automated production. Today, the established processes for the production of complex high-performance fiber composite components (Resin Transfer Molding (RTM) and prepreg) predominantly use manual operations. This is due on the one hand to the sensitivity of these textile fabrics and, on the other hand, to the complexity of the required work steps. In addition, handling is made more difficult by the shape instability and air permeability of the fiber structures. This concerns both preimpregnated sticky semi-finished products as well as dry fiber structures.

The acceptance of new manufacturing processes, especially in the automotive industry, depends essentially on the degree of automation and the associated costs. The demands on a completely automated process chain and especially on the handling technology are high. What is required are damage-free and reproducible handling processes with simultaneously short cycle times. Precise positioning of blanks and the realization of complex deposition patterns and layer structures for demanding geometries are important for process safety, where the stress-oriented deposition of the fiber reinforcement structures according to the fiber orientation is decisive for the subsequent component quality.

A basic prerequisite for economical and reproducible handling of textile structures is a stable preform structure. A textile preform is understood to mean a near-net shape, preferably dry, fiber structure with a load-compatible fiber structure, also called a fiber preform. The development of suitable preforming technologies is crucial for the cost-effectiveness of injection procedures, since this can drastically reduce the handling and laying effort and thereby also the cycle times during production. In addition, post-processing machining should be kept to a minimum after injection. Despite the higher cost of preforms compared to simple semi-finished products, the overall cost of a fiber-reinforced plastic component may be significantly lower than traditional methods.

According to the state of the art, layers are usually sewn together by means of auxiliary threads in order to stabilize preforms or to join sub-preforms. If it is merely a matter of fixing or joining sub-preforms or individual fiber layers, this is called confectionery sewing.

For the processing of three-dimensional fiber structures exist robot-guided one-side sewing heads that can do without a Nähkopfunterteil and therefore can sew large and complex structures. Almost all Einkopfnähverfahren have the common feature that they need for the thread feedthrough and thread transfer a space or a soft pad below the fabric structure to be processed or the preform. Therefore, can not be sewn directly in the mold. In addition, the layer thickness to be processed is limited. Limiting factor is z. As in the blind stitch sewing technique, the geometry (radius) of the inserted sheet needle and in the two-needle sewing technique, the meeting point of the needle tips.

In addition, the seams introduced into the preform adversely affect the properties of the later composite component. Thus, the in-plane characteristic values (tensile and compressive strengths) of the composite component are greatly reduced by corrugations, fiber displacements and damage to individual filaments. These so-called ondulations lead to preferred directions when buckling fiber composite components under pressure. Furthermore, the thread tension leads to a constriction of the roving, which accumulates resin in the constricted areas. These resin accumulations act as notch sites and are thus potential crack propagation zones.

Another disadvantage of sewing is the often not inconsiderable entry of additional yarn into the fiber structure, which leads to an unnecessary increase in mass of the preform in fixing seams. In some sewing methods, up to 17 meters of yarn are fed into the component for one meter of seam.

To fix the various textile layers of a preform often special binder systems are used. These are solid or liquid epoxy resins or co-polyamides at room temperature, which are applied to the layers over a wide area and are heated for connection in the preform state. These adhesives have become established in various industries. However, this surface-applied hardened adhesive layer greatly influences the impregnation process of the matrix resin in the RTM / T-RTM process (under the T-RTM process is meant a thermoplastic RTM process in which a thermoplastic reactive resin system is used instead of the usual thermosetting resin system), as this reduces the permeability of the reinforcing fibers and thus reduces the mechanical properties of the final product. In addition, a possibly additionally required sewing process (structural seam for improving the out-of-plane properties) is made more difficult because the needle-punching forces are considerably increased by the surface-applied and cured binder.

Therefore, the process of bonding is complex in complex components, since the binder powder for good permeability must be applied evenly and in the correct dosage. Another negative side effect of the lower permeability of the fiber structures is the increase in the infiltration time, which has a negative effect on the total cycle time of the manufacturing process.

Starting from the prior art, it is an object of the present invention to provide a method and an apparatus for fixing textiles to each other, which overcomes the above-mentioned problems. In particular, the method preferably avoids impurities and permits high textile permeability. The process is intended to prevent constrictions and bumps, thereby avoiding areas where resin accumulates. The method should preferably be feasible with any number of textile layers and an additional mass entry should be kept low. Preferably, the method should be executable directly in a mold and manage without space below the textiles to be joined. Preferably, the method should also allow handling of the textile products.

The above objects are achieved by the method for fixing at least two textiles to each other according to claim 1, by the apparatus for fixing at least two textiles according to claim 10 and the textile product according to claim 16. The respective dependent claims indicate advantageous developments of the method according to the invention, the device according to the invention and the textile product according to the invention.

According to the invention, a method for fixing at least two textiles to one another is first of all specified. In this case, fixing is understood to mean the production of a firm connection between the at least two textiles, which comprises, in particular, joining and / or joining. A textile is understood to mean a preferably flexible material which has a composite of fibers. Particularly advantageously, the method is applicable to textile layers, d. H. extensively expanded textiles, especially those that extend substantially two-dimensionally when spread on a plane.

According to the invention, at least two textiles are now arranged adjacent to one another in those regions in which the textiles are to be fixed to one another or joined or joined together. If no intermediate layers, in particular no intermediate textile layers are provided, the at least two textiles preferably touch in these areas.

It is now in those areas in which the fixation or connection is to be made, inserted into the at least two textiles with at least one stitch, so that at least one puncture channel is formed, which extends through the at least two textiles. The puncture channel should extend beyond those interfaces where the fabrics border or touch each other. If textile layers are joined together, then the puncture channel should preferably extend completely through the layers to be fixed together.

Adhesive is now introduced into the at least one puncture channel in such a way that this adhesive glues the textiles to be fixed together. The puncture channel is continuous between the textiles to be fixed together, so that the supply of the adhesive can be made from one side of the arrangement of textiles.

Preferably, the textiles are joined together with a plurality or plurality of such stitches.

To speed up the process, it is preferable if the process is performed simultaneously with a plurality of punctures and puncture channels.

Thus, according to the invention, at least two textiles can be fixed to one another by initially placing the textiles next to each other, then performing the piercing, and then inserting the adhesive into the piercing channel (s).

It is advantageous if the adhesive is cured during and / or immediately after insertion. This can be achieved that the compound produced does not dissolve again in the course of further processing. Particularly suitable adhesives are those which are actively curable. Such adhesives may be adhesives that are curable by means of electromagnetic radiation, such as light, UV light or microwave radiation. Also suitable are adhesives which are curable by means of ultrasound. The adhesives may u. a. thermoplastic or thermosetting adhesives.

If the procedure is performed with more than one puncture and puncture channel, these punctures can be made simultaneously or sequentially. In particular, if the punctures are produced in succession and adhesive is introduced successively into these punctures, hardening during and / or immediately after insertion ensures that the connection no longer releases at already completed fixation points in the course of producing the further fixations.

According to the invention, the puncture channels can be produced by means of one or more needles, which are inserted into the at least two textiles. The needles are hereby punctured so that they pierce the textiles to be joined together and preferably puncture in the case of textile layers.

Particularly preferred according to the invention needles are used which have a hollow channel through which the adhesive can be introduced into the puncture channel. In this case, the needle may be punctured and the adhesive may be introduced through the needle into the puncture channel while the needle is withdrawn from the puncture channel.

If the curing of the adhesive by means of electromagnetic radiation or by means of ultrasound, the electromagnetic radiation or the ultrasound can thus be irradiated during extraction of the needle or immediately after the needle has left the piercing channel corresponding to her.

In a preferred embodiment, the method according to the invention may comprise a handling or movement of the textile product resulting from the fixing. For this purpose, the adhesive can be cured in the manner described above, as long as the adhesive present in the puncture channel is still in contact with the needle. It is thus the textile product so glued to the needle. The product can then be moved or transported. After completion of the handling process, the adhesive connection can be disconnected. For this purpose, the at least one needle can be subjected to ultrasound.

The textile product produced by the process according to the invention can u. a. a semi-finished fiber product, preferably a dry semi-finished fiber product, and / or form a preform.

A particular advantage of the method according to the invention is that the method can be carried out independently of the position and on which background the textiles are present. It is therefore preferred if the textiles, in particular textile layers, are already arranged in a mold, such as a preforming tool. The textiles can in this case first be arranged in the mold according to their target shape. It can then be carried out the inventive method, in particular a fixation in the target shape is possible.

The method according to the invention thus makes it possible to produce a textile product and to handle it, in particular dry semifinished fiber products, with minimal use of adhesives, which are ideally chosen in a system-compatible manner. In this case, as in the case of ready-made sewing, a fixation is made at locally defined locations, for example a preform, but without introducing an additional thread into the fiber structure. The previous task of the sewing thread is taken over in the process according to the invention by a locally introduced, preferably system-compatible adhesive system. In this case, minimal quantities of adhesive similar to a seam are introduced into the textile structure and cured there.

The invention also provides an apparatus for carrying out the method described above. The device has at least one puncturing device with which at least two textiles for producing a puncture channel can be pierced there, where the at least two textiles are to be fixed to one another. The puncture channel is thereby produced so that it extends through the at least two textiles. The device according to the invention also has at least one adhesive device with which adhesive can be introduced into the at least one puncture channel in such a way that it glues the at least two textiles together. The device according to the invention can also have at least one curing device, with which the adhesive is curable during and / or after the introduction. Such a curing device may in particular be a light source, a UV light source, a laser, a microwave source or an ultrasound source.

The puncturing device is preferably a needle, which is particularly preferably configured as a hollow needle, so that the adhesive can be guided through the needle into the puncture channel. To speed up the process, several or a plurality of puncture devices or needles may be provided. Although basically every needle can be equipped with its own curing device, it is preferred if several needles, for example several needles in a row, have a common curing device. For example, to multiple tips of needles by means of a light source, preferably a laser, Light can be irradiated through mirrors. The light is then generated by a light source and preferably deflected by means of a mirror for each needle on the tip of the corresponding needle.

According to the invention, a textile product is additionally provided which has at least two textiles which are fixed to one another at at least one splice. The fixation here is that in at least one extending through the textiles puncture channel adhesive is present, which glues or joins the textiles together.

In the context of this application, a puncture channel can be understood as an area in the corresponding textiles which is opened by the puncture device. If the puncturing device is sufficiently fine or the distance between fibers of the textile is sufficiently large, the needle can also pierce between the fibers without widening the intermediate region. That intermediate region into which the needle is inserted is then understood as a puncture channel. It is possible, depending on the textiles to be joined, that the adhesive is not present exclusively in the puncture channel, but seeps into the surrounding textile up to a certain distance from the puncture channel. The adhesive then exists in a limited area around the puncture channel. However, the procedure of introducing the adhesive is also in this case as described above.

Preforming and handling of textile fabrics is an important key to the economic implementation of RTM technology. The availability of automated solutions is the prerequisite for the mass production capability of these processes. By applying the invention, it is possible to automatically stabilize preforms for highly reinforced fiber composite components based on textile fabrics, such as mats, fabrics or scrims, and reactive matrix systems. The known disadvantages of the established binder and sewing techniques are avoided.

General application areas are all areas in which established confectionary sewing and barking techniques are used for preform stabilization. Furthermore, as described above, this invention can also be used in the field of handling technology for dry textile fabrics.

Possible applications for the invention can be found in the aerospace industry, automotive industry, sports and leisure industry and in medical technology, where components and structures with special requirements for geometry and mechanics in larger quantities are required.

In the following, the invention will be explained by way of example with reference to some figures. Here, the same reference numerals mean the same or corresponding features. The features mentioned in the examples can also be realized independently of the specific example in any combination.

It shows

1 an overview of different seams, in which the present invention can be used,

2 a sequence of the method according to the invention with a device according to the invention, and

3 a device according to the invention.

1 shows an overview of various seams in a textile product, which can be produced by the method according to the invention.

Edge protection seam 21 :

In the fabrication process, the blanks are generally cut out by the meter. The textile fabrics, such as fabrics or scrims, tend to fraze the cut edges. One way to protect the edge of the preform is to have a circumferential seam 21 (Overlock seam) at the edge area in the textile bring. For fiber composite components, this type of edge protection is rather critical, because on the one hand, the edges are rounded off, which leads to resin nests. On the other hand, the proportion of the incorporated suture is high, so that it comes in the border area to an additional collection of suture. In accordance with the present invention, the edge seal is made by the entry, ie, spraying or injecting, of system compatible adhesive.

Positioning and stitching 22 :

The textile blanks are stacked or positioned on each other before joining. To ensure the handling of the layers, the blanks are fixed to each other by stitching and positioning seams. The seams have no significance from a structural mechanical point of view, however, the introduced sewing threads reduce the in-plane properties of the subsequent composite.

shaping seam 23 :

The production of preforms is often associated with forming or Drapieroperationen. Forming seams are used by Forming operations to fix geometry obtained in their form. They have no significance from a structural mechanics point of view, however, the introduced sewing threads reduce the in-plane properties of the later composite.

assembly seam 24 :

Depending on their complexity, preforms are manufactured as sub-preforms (subcomponents), which are then completed in one or more assembly processes. The subcomponents may have one or more parts or blanks. The joining of the sub-preforms is done by montage seams. Shown is also a contour seam 25 ,

2A shows schematically the implementation of the method according to the invention with a device according to the invention. In a first step, two textiles are used as textile layers 1a and 1b in a preforming tool 2 arranged, here only a section of the preforming tool 2 is shown. The textile layers 1a and 1b are arranged against one another and are to be fixed to one another or connected to one another by means of the method according to the invention. In the example shown here are now above the textile layers 1a . 1b two needles 3a and 3b arranged as puncture devices.

2 B now shows the production of two puncture channels, which are through the textile layers 1a . 1b extend. For this, the needles 3a . 3b into the textile layers 1a . 1b stabbed. After puncture channels 4a and 4b by piercing the needles 3a . 3b can be made, the introduction of adhesive 16 into the puncture channel. For this purpose, in the example shown adhesive 16 through the needles 3a . 3b which are called hollow needles 3a . 3b are designed to the top in the puncture channel 4a . 4b directed into it. During the introduction of the adhesive 16 become the needles 3a . 3b from the puncture channels 4a . 4b moved out to that position as in 2C is shown. In the example shown, the adhesive 16 cured immediately during insertion into the puncture channel. For this purpose, light, such as UV light or laser light 5 which is from a light source 6 is generated on the tips of the needles 3a . 3b irradiated. In the example shown, the light becomes 5 for both needles 3a . 3b through a common light source 6 generated and then by mirror 7a . 7b directed to the appropriate tip. The light source 6 is here in operation while the needles 3a . 3b from the puncture channels 4a . 4b to be moved out.

2C shows the state in which the needles 3a . 3b completely out of the puncture channels 4a . 4b were pulled out, leaving the tips of the needles 3a . 3b now slightly above the surface of the upper textile layer 1a are positioned. The supply of glue 16 through the needles 3a . 3b This was not stopped immediately, so the needles 3a . 3b still with the glue 16 are in contact. It is still light 5 through the light source 6 irradiated on the tips of the needles, leaving the glue 16 in contact with the needles 3a . 3b is cured.

Is the curing of the adhesive 16 completed, the light source can be 6 be turned off, so that in 2D shown state is present. The needle tips adhere here to the introduced adhesive 16 , As in 2E Now, the entire textile product can be shown by means of the device and its needles 3a . 3b be raised and relocated.

According to the invention, the adhesive 16 be thermoplastic or thermosetting adhesive, which can be melted or cured by irradiation of electromagnetic radiation. It is also an adhesive 16 conceivable, for example, by means of ultrasound or microwaves curable. The in 2 For the use of ultrasound or microwaves, the structure shown is correspondingly reconfigured such that the ultrasound or the microwaves on the adhesive 16 in the puncture channel 4a . 4b is einstrahlbar.

For certain applications, the activation or hardening or melting of the adhesive by means of ultrasound is advantageous because it allows the needles to be easily detached from the adhesive by exciting the needles with ultrasound at a suitable frequency. As a result, the device according to the invention can also be used particularly advantageously as a handling unit.

3 shows a concrete embodiment of a device according to the invention, with which the inventive method is feasible. The device has a needle 3 as puncture device. The needle 3 can in this case be moved in its longitudinal direction, so that a plurality of puncture channels can be generated successively when the device is moved past a textile arrangement. To avoid unevenness and for local compaction of the fiber structures (required contact pressure for bonding), the device has a presser foot 10 on, which by means of a foot holder 11 attached to an underside of the device. The needle 3 is here by the foot 10 movable therethrough.

The device also has two adhesive metering cylinders 12a . 12b on, in which adhesive can be accommodated. It can be used in this case 1-component adhesive or 2-component adhesive. The device shown also has an energy source 6 which, for example, a laser 6 can be. The energy source 6 is arranged so that with it the glue at the top of the needle 3 can be activated or melted or curable. As a light source 6 can be the source of energy 6 directly on the tip of the needle 3 be aligned.

The device shown also has a connection flange 13 on, with which the device according to the invention can be mounted on a robot. By guiding the device shown on a robot arbitrarily extending joints can be generated.

The adhesive is from the adhesive dosing cylinders 12a . 12b through the needle 3 to the needle tip leitbar. If a 2-component adhesive is used, the cylinders can 12a and 12b containing the two components of the adhesive separately. Before the adhesive is introduced into the needle, then the components are in a mixing chamber 14 first mixed and then into the injection needle 3 directed.

The device shown is essentially on a carrier plate 15 mounted, with the needle 3 through an opening in the carrier plate 15 passes through, leaving the tip of the needle 3 below the carrier plate 15 lies. The presser foot 10 with the foot holder 11 are accordingly also at the bottom of the carrier plate 15 arranged. On one upper side of the carrier plate, on the one hand, there are the adhesive metering cylinders 12a . 12b as well as a mechanism for moving the needle 3 and optionally the mixing chamber 14 , The light source 6 is also above the support plate 15 arranged and aligned so that they are on the support plate 15 passes over to the top of the needle.

Claims (18)

Method for fixing at least two textiles to each other, wherein the at least two textiles are placed together where they are fixed to each other, into the at least two textiles where they are fixed to each other, is inserted, so that at least one puncture channel is formed, which extends through the at least two textiles and Adhesive is introduced into the at least one puncture channel so that it glues the at least two textiles together. Method according to the preceding claim, characterized in that the adhesive is cured during and / or immediately after insertion. Method according to one of the preceding claims, characterized in that by means of at least one needle, which has a hollow channel through which adhesive is conductive, is inserted into the at least two textiles and that the adhesive is passed through the hollow channel in the puncture channel. Method according to one of the preceding claims, characterized in that the at least two textiles form a semi-finished fiber product, preferably a dry semi-finished fiber product, and / or a preform. Method according to one of the preceding claims, characterized in that the adhesive is curable by means of electromagnetic radiation, preferably by means of light and / or microwave radiation, particularly preferably by means of UV light and / or by means of ultrasound. Method according to the preceding claim, characterized in that the electromagnetic radiation and / or the ultrasound is irradiated onto the adhesive, while the at least one needle is withdrawn from the at least one puncture channel and / or immediately after the at least one needle the at least one puncture channel has left. Method according to one of the preceding claims, characterized in that the adhesive is cured so that it connects the at least one needle with the textiles and / or glued after the at least one needle has left the corresponding puncture channel. Method according to one of the preceding claims, characterized in that the at least two textiles are moved and / or handled after fixing by means of the at least one needle and / or the needle is released from the textiles by applying ultrasound to the needle. Method according to one of the preceding claims, characterized in that the at least two textiles are arranged prior to piercing in a mold, a molding tool or a preforming tool. Method according to one of the preceding claims, characterized in that at least one or all of the textiles is an extensively extended textile layer. Device for fixing at least two textiles to each other with at least one piercing device with which at least two textiles for producing at least one piercing channel extending through the at least two textiles can be pierced there, where the at least two textiles are fixed to one another, and with at least one adhesive device for introducing adhesive into the at least one puncture channel so that the at least two textiles are glued together. Device according to the preceding claim, characterized by at least one curing device for curing the adhesive during and / or after the introduction. Device according to one of the two preceding claims, characterized in that the curing device is a light source, preferably a UV light source, a laser, a microwave source and / or an ultrasound source. Device according to one of the three preceding claims, characterized in that the piercing device is a needle with a waveguide as an adhesive device, preferably that the piercing device is a hollow needle. Device according to one of claims 11 to 14, characterized by a plurality of puncture devices, wherein electromagnetic radiation can be irradiated to adhesive in the corresponding puncture channels from a common source for several puncture devices source. Device according to one of claims 11 to 15, characterized in that with the device, a method according to any one of claims 1 to 10 is feasible. Textile product comprising at least two textiles, the at least two textiles being fixed to one another at at least one gluing point, at which glue in at least one prick extending through the at least two textiles joins or glues the at least two textiles together. Textile product according to the preceding claim, characterized in that the textile product is produced by the method according to one of claims 1 to 10 or can be produced.

Images